A conventional hand tool for reaching an object (a screw, for example) located in a deep recess generally uses an extension rod which has one end connected to the driving or active member so that the power may transfer to the extension rod, and the other end of the extension rod is connected to a screw bit for example to rotate the object. Nevertheless, when the active member is driven by an electric power tool, there is a time lap between the electric power tool and the screw bit. In other words, the torque could be too much for the object and the surface where the object is located which is damaged. This is partially because the length of the path that the power is to be transferred is too long so that the user's hand cannot precisely feel the feed back of the resistance from the object and the receive of the feed back is a little bit delay. Therefore, extra torque is sent to the screw bit to overly screw the object.
Although at least one torque adjustable tool is disclosed and capable of keeping the output torque below a pre-set value. But the tool is useless if the user does not need any output torque restriction, in this situation, the user has to use another tool that does not have any feature to restrict the output torque.
The present invention intends to provide a torque adjustable tool that the user can optionally set the tool to be a torque adjustable tool or a simply a torque tool without any output adjusting feature. By the tool of the present invention, the output torque can be set so as to avoid damage to the object, and the output torque can be set to be the same as the driving power without any restriction.